List your scariest alien movies?

Wow @toman, my list is almost identical to yours, I'm also glad that you give AR some credit considering all the undeserved hate it gets (a lot in this forum it seems) 

1. Alien (still unsettling, ominous and downright scary to this day) 

2. Aliens (masterfully builds up the tension just like Alien with an eerie ghost colony, and the Queen is terrifying) 

3. Alien Resurrection (When the Queen makes her appearance, the xenos themselves - suit version- fantastic job, the Newborn design, animatronic and sound effects. Ripley clone room. Bone chilling)

4. Alien Covenant (some jump scares, the dead city was creepy, and some of the music tracks did a great job of lifting the sense of horror and tension)

5. Alien 3 (a few scary scenes) 

6. Prometheus (Not very scary)

Only Brett death scares me 

None of them really scare me anymore. If anything would really scare, it would be being completely vulnerable to the Xeno. That said, I would have to pick Alien and Alien 3.

I just watched Alien about a week before I saw Covenant.  I recorded it off of the TV and watched it later.  I think the TV switches out clips of the movie with others to make it less scary.  So when I watched Alien this time, it was the scary version because when Dallas was crawling through those air ducts, he stumbled upon the Xeno and I uncontrollably screamed.  I can't remember my first watch of the movie Alien, but after watching it just recently, I think the first viewing would have been epic.  I remember watching Aliens a long time ago and there was a part where I thought everything was safe.  Whoever was left was flying away, then all of a sudden, a Xeno landing on the cockpit glass.  I almost turned it off at that point because I was so scared.  I remember Alien Resurrection being fairly scary too.  Especially the part when the Xeno's start swimming after the people.  In Prometheus, I was freaking out over David touching everything and the holograms too.  In Alien: Covenant, I was on edge the whole time, but nothing made me scream or made me want to get up and leave.  It wasn't scary enough!  Alien 3 had some good suspense in it too.

"Scary" is tough to pin down. For some, it is gore; for others it is suspense. Personally, gore doesn't bother me much except when used effectively with other elements like sound and context. Nothing really scares me in movies- "uncomfortable" might be a better description for me. In Resurrection, the failed clones scene was not scary but the implications that experiments probably horrific and painful to the subjects were going on for some time was pretty deep and uncomfortable to me. Scary really only applies on a psychological level to me- probably why Alien and Alien 3 scare as I mentioned above.

Covenant....it was scarily bad (sorry, couldn't help myself it was too easy lol)